Separation, and especially on line separation of target antigens from biological fluids for diagnostic and/or curative purposes is often desirable, especially where the biological fluid is a whole blood or other bodily fluid. Among frequently isolated and/or separated target antigens are diseased cells (e.g., T4-helper cells infected with HIV virus), non-diseased cells (e.g., adult stem cells), various bacteria, and viruses.
There are numerous methods of on line separation or isolation of target antigens known in the art, and such methods may be grouped into one of two categories. For example, in a discontinuous separation, a biological fluid is isolated from a source (e.g., blood is drawn from a human) and subsequently processed for the desired target antigen. Most commonly, such methods include centrifugation for relatively large volumes of biological fluids, or magnetic separation for relatively small volumes. In either case, the processed fluid may then be reintroduced into the human. While discontinuous separation is generally relatively effective, various disadvantages remain. Among other things, processing of the isolated biological fluid typically requires transfer of the fluid among a multitude of containers, which significantly increases the likelihood of contamination of the processed sample. Furthermore, depending on the particular the volume of the isolated fluid, multiple samples need to be drawn for sufficient amount of target antigen.
On the other hand, in a continuous separation, a biological fluid is directly routed from a source (e.g., via i.v. line) into a separation unit and continuously processed for the desired target antigen before the depleted fluid is rerouted into the source. Most commonly, such methods include gradient centrifugation, or on line magnetic separation. While discontinuous separation is generally advantageous with respect to simplified sample handling, all or almost all of the on line separations require relatively expensive and intricate equipment. Consequently, many continuous separation methods and configurations present various challenges. For example, continuous centrifugation equipment (e.g., as the equipment used in thrombocytophoresis) typically requires control by highly trained professionals. For magnetic separation, cells or other target antigens are separated by virtue of their magnetic moment, thereby typically limiting separation efficiency at desirable flow rates.
Although various configurations and methods for isolation and/or separation of one or more components from blood are known to the art, all or almost all of them suffer from one or more disadvantage. Therefore, there is a need to provide apparatus and methods for improved isolation and/or separation of components from blood.